i already know the answer in #1...mY problem is #2 & #3....
1. if the power to the motor is shut off while the motor is running at 3000 rpm and a brake is applied, how much heat in joules will be dissipated in the brake in order to bring the motor to a stop?
ans. 138, 527 J
2. suppose the motor has a bearing shaft diameter of 3.2 cm and the coefficient of friction of each bearing is 0.008. find the torque of friction of the bearings.
a. 0.0320 N-m
b. 0.314 N-m
c. 0.411 N-m
d. 0.481 N-m
3. referring to problem 1, suppose that, instead of the brake being applied, the motor with the power cut off is allowed to run until it is brought to a stop by the torque of friction of the bearings. how long will the armature take to come to a stop?assume all other losses (such as windage) are zero.
a. 420 sec
b. 840 sec
c. 1260 sec
d. 2810 sec
heLp me solve these pLease!!!thanks!!^_^
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